Merge pull request #169 from orcaprotocol/willkim/qsp-14

fix: QSP-14

contracts/SafeTeller.sol

@@ -1,10 +1,11 @@
 pragma solidity ^0.8.7;
 
+import "./utils/DelegateSetupHelper.sol";
 import "openzeppelin-contracts/utils/Address.sol";
 import "./interfaces/IGnosisSafe.sol";
 import "./interfaces/IGnosisSafeProxyFactory.sol";
 
-contract SafeTeller {
+contract SafeTeller is DelegateSetupHelper {
     using Address for address;
 
     // mainnet: 0x76E2cFc1F5Fa8F6a5b3fC4c8F4788F0116861F9B;
@@ -384,14 +385,4 @@ contract SafeTeller {
             IGnosisSafe.Operation.Call
         );
     }
-
-    // TODO: move to library
-    // Used in a delegate call to enable module add on setup
-    function enableModule(address module) external {
-        require(module == address(0));
-    }
-
-    function delegateSetup(address _context) external {
-        this.enableModule(_context);
-    }
 }

contracts/utils/DelegateSetupHelper.sol

@@ -0,0 +1,21 @@
+pragma solidity 0.8.7;
+
+// These functions are not used by the SafeTeller directly, so have been moved
+// to their own contract
+contract DelegateSetupHelper {
+    // In our `SafeTeller.createSafe()` function, we call `GnosisSafeProxyFactory.createProxyWithNonce()`
+    // with a callback to this `delegateSetup()` function. The proxy factory will then call this function
+    // via a delegate call.
+    // In the context of this delegate call, `this` will refer to the proxy factory, which then in turn makes a
+    // delegate call to GnosisSafe, and `this` will then refer to GnosisSafe
+    // therefore this function will call `GnosisSafe.enableModule()`, which is inherited from `ModuleManager`.
+    function delegateSetup(address _context) external {
+        this.enableModule(_context);
+    }
+
+    // This function is here solely to allow compilation.
+    // This function should not be called, see the above doc block for explanation.
+    function enableModule(address) external {
+        revert("should not be called");
+    }
+}